l'^6 INSI-XTS ATTACKIX(; W KKDS IX MIXXKSOTA. 



(landelioii Taraxacum ofticiJialc Web., the seeds of which it gener- 

 ally infests, destroying approximately one-cpiarter of them. 



From my own observations of the weed insects in Minnesota 

 the Milk Vetch I Astroi^alns canadeiisis L. j is very probably kept 

 from ])eing a noxious weed of the hrst order l)v its insect enemies, 

 h)ur species of which almost completeK- destro\- the seeds. 



On the other hand, weeds har])or many oi our insect i)ests and 

 are often undoubtedly the starting point of insect outbreaks. San- 

 derson includes crop rotation, fall ])lo\\ing-. clean culture, as well 

 as weeds among his farm or cultural methods for controlling insects, 

 which ])ractices are beginning' to be recognized as of increasing 

 im])ortance in farm economy. esi)ecially in case of the field-crop 

 insects where spraying is imj^racticable. It is well known that 

 many insects feed on weeds during the early part of the season 

 uiUil the cultixated crop is a\ailable. as. for example, the corn root 

 aphis. This louse maintains itself on yoimg smartweed and foxtail 

 grass at hrst, and if corn is not planted, it will feed, according to 

 Forbes, on puslane and pigeon grass. 



Many of the jjeetles that feed on solonaceous plants also get 

 their start in spring on weeds of the same family. The strawberry 

 llea-beetle is said to deposit its eggs on the evening ])rimrose, its 

 ondy other food i)lant. ( )bviously, such a weed shoidd not be 

 tolerated near strawberry beds. 



The dominant tarnished ])lant bug, a well-known, formidable 

 ])est. has a wide range of food plants, including such weeds as 

 golden rod. aster, daisv, fleabane, wild carrot, and nuillein. 



The common evening prinu'ose beetle. Tylodcniia foi'colata 

 was re])orte(l in 1897 as verv injurious to strawberries in British 

 Columbia. This species is not generally known as a ])est of straw- 

 berries : but a closely related form. T. I'rai^aria. is familiar to many 

 as the strawberrv crown borer. An attempt was made to find out 

 wheth.er T. foi'colata would attack strawl)erries in Minnesota. 

 Four wire cages with strawberry plants were used and beetles 

 placed in them throughout the season. The beetles \vere taken 

 from the e\ening ])rimrose during their ovi])osition ])erit)(l, and 

 while thev fed on the leaves and pedicels voraciously, ihey failed 

 to oviposit in the crowns. It appears then that we have nothing to 

 fear from this insect in Minnesota. In fact, it ought to be con- 

 sidered useful, in that it hel])S to destroy weeds. 



SimilarK- the common knotweed leaf beetle, iiastroidca holy- 

 i^oni. found feeding on wild liuckwheat ( polyi^oiiinii coiii'olz'itliis) 

 which is related to buckwheat, was also tested, .\ltho the beetles 



